October 6, 2008

Study: Insecticide Decimates Tadpoles

A U.S. study suggests the common insecticide malathion can decimate tadpole populations, killing them indirectly at doses too small to kill them directly.

University of Pittsburgh researchers wanted to determine the environmental impact of the use of malathion -- the most popular insecticide in the United States.

The scientists discovered gradual amounts of malathion that were too small to directly kill developing leopard frog tadpoles instead sparked a biological chain of events that deprived them of their primary food source -- bottom dwelling algae, or periphyton, which tadpoles eat.

"As a result, nearly half the tadpoles in the experiment did not reach maturity and would have died in nature," the researchers said.

The results of the National Science Foundation-funded research builds on a nine-year effort by Associate Professor Rick Relyea to determine whether there is a link between pesticides and the global decline in amphibians. Relyea said amphibians are considered an environmental indicator species because of their sensitivity to pollutants and their deaths might foreshadow the poisoning of other, less environmentally sensitive species -- including humans.

Relyea and study co-author Nicole Diecks report their research in the journal Ecological Applications.